Ann Thorac Surg 1997;63:1663
© 1997 The Society of Thoracic Surgeons
Invited Commentary
Invited Commentary
Thomas P. Graham, Jr, MD
Division of Pediatric Cardiology Vanderbilt University School of Medicine Room D-2220 MCN Nashville, TN 37232-2572
See also page 1657.
This report of successful biventricular repair in 4 of 5 infants with severe right ventricular--dominant atrioventricular septal defect and left ventricular hypoplasia represents a potentially exciting new breakthrough in the management of this complex abnormality. The preoperative data indicate such a severe ventricular imbalance, it is highly unlikely that any other group would have attempted biventricular repair in these patients.
In looking at the quantitative information, one does have to question the preoperative volume data in terms of absolute numbers. Three of the 5 patients had left ventricular volumes preoperatively that were approximately 2 mL. If one assumes an ejection fraction of 0.75, a heart rate of 160, and a body surface area of 0.25 m2 (numbers that would be possible for these infants), the left ventricular output would be about 1.0 L•min-1•m-2. If left ventricular output was the only source of aortic flow, it is unlikely these patients could have survived preoperatively with systemic blood flow this low. It is probable that there was a secondary source of aortic flow-either undetected ductal right-to-left shunting or right ventricular ejection across the ventricular defect into the aorta. These theoretic calculations emphasize the importance of very careful preoperative and postoperative measurements.
Before there is a major change in surgical practice to select biventricular repair for virtually all unbalanced atrioventricular septal defects with left ventricular hypoplasia, however, there are important caveats, which are mentioned by van Son and coauthors. It appears that most of the patients in this group had a restrictive interventricular communication, antegrade ascending aortic flow from the left ventricle, either a closed ductus or left-to-right ductal flow, and similar oxygen saturations in the upper and lower extremities. As more patients like these begin to undergo attempted biventricular repair, it will be important that the particular echocardiographic measurements demonstrated in this report are made before and after operation and that physiologic data on ductal shunting, oxygen saturations, and antegrade flow from the left ventricle be documented carefully. It is to be hoped that the concept of potential left ventricular volume as demonstrated in this study of van Son and colleagues will prove useful as a predictor of postoperative outcome.
Despite the questions regarding the accuracy of the volume determination, the results speak for themselves. Hopefully this approach can extend the limits for biventricular repair in patients with this complex abnormality.
Related Article
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Predicting Feasibility of Biventricular Repair of Right-Dominant Unbalanced Atrioventricular Canal
- Jacques A. M. van Son, Colin K. Phoon, Norman H. Silverman, and Gary S. Haas
Ann. Thorac. Surg. 1997 63: 1657-1663.
[Abstract]
[Full Text]
